Regulation of Glycolysis by SMAD5 in Glioma Cells: Implications for Tumor Growth and Apoptosis

The Warburg effect serves as a crucial aspect of tumor metabolism, where tumor cells preferentially rely on glycolysis, despite its lower efficiency, over oxidative phosphorylation for energy production even under aerobic conditions. This reprogramming of glucose metabolism confers glioma cells with the capacity for survival and proliferation. Serving as a messenger for regulating transforming growth factor beta, intracellular pH, cell metabolism maintaining cellular bioenergetic homeostasis, SMAD family member 5 (SMAD5) plays a pivotal role in the malignant progression of glioma cells and aerobic glycolysis. Hence, we have identified the expression and function of SMAD5 in human glioma cells, aiming to clarify its role in glycolysis. qRT-PCR and Western blot, reveal that SMAD5 is significantly overexpressed in glioma cells. Knocking down SMAD5 can effectively suppress the proliferation and invasion of glioma cells, while promoting apoptosis, furthermore, downregulation of SMAD5 in vivo has been shown to significantly reduce the growth of xenograft tumors. Conversely, overexpressing SMAD5 enhances the proliferative and invasive capabilities of glioma cells, while suppressing apoptosis. Concurrently, alterations in the expression level of SMAD5 exert an impact on the expression of glucose transporter GLUT1 and crucial enzymes involved in glycolysis, namely HK2 and PKM2, ultimately influencing the glycolytic capability of glioma cells. Specifically, knockdown of SMAD5 suppresses glycolysis, whereas its overexpression enhances glycolytic activity. In conclusion, our data demonstrate that SMAD5 can influence the proliferation, invasion, and apoptosis of glioma cells by modulating glycolysis. This finding holds potential for the development of novel metabolic treatment strategies for glioma.